/u/ and /oʊ/ are "conservative" in this region, and do not undergo the fronting that is common in some other regions of the United States.

In addition to being conservative, /oʊ/ may be monophthongal[o]. The same is true for /eɪ/, which can be realized as [e], though data suggests that monophthongal variants are more common for /oʊ/ than for /eɪ/, and also that they are more common in coat than in ago or road, which may indicate phonological conditioning. Regionally, monophthongal mid vowels are more common in the northern tier of states, occurring more frequently in Minnesota and the Dakotas but much rarer in Iowa and Nebraska.[1] The appearance of monophthongs in this region is sometimes explained due to the high degree of Scandinavian and German immigration to these northern states in the late nineteenth century. Erik R. Thomas argues that these monophthongs are the product of language contact and notes that other areas where they occur are places where speakers of other languages have had an influence such as the Pennsylvania "Dutch" region.[6] An alternative account posits that these monophthongal variants represent historical retentions. Diphthongization of the mid vowels seems to have been a relatively recent phenomenon, appearing within the last few centuries, and did not affect all dialects in the UK. The monophthongs heard in this region may stem from the influence of Scots-Irish or other British dialects that maintain such forms.[citation needed] The fact that the monophthongs also appear in Canadian English may lend support to this account since Scots-Irish speech is known as an important influence in Canada.

Some speakers exhibit raising of /æ/ before voiced velars (/ɡ/ and /ŋ/), with an up-glide rather than an in-glide, so that bag sounds close to beg or the first syllable of bagel in other dialects (other examples of where this applies include the word flag and agriculture). Sometimes the two are merged.[4]

Raising of /aɪ/ is found in this region. It occurs before some voiced consonants. For example, many speakers pronounce fire, tiger, and spider with the raised vowel.[7] Some speakers in this region raise /aʊ/ as well.[8]

The onset of /aʊ/ when not subject to raising is often quite far back, resulting in pronunciations like [ɑʊ].

The words roof and root may be variously pronounced with either /ʊ/ or /u/; that is, with the vowel of foot or boot, respectively. This is highly variable, however, and these words are pronounced both ways in other parts of the country.

The Mary-marry-merry merger: Words containing /æ/, /ɛ/, or /eɪ/ before an "r" and a vowel are all pronounced "[ɛ]-r-vowel," so that Mary, marry, and merry all rhyme with each other, and have the same first vowel as Sharon, Sarah, and bearing. This merger is widespread throughout the Midwest, West, and Canada.

North Central speech is rhotic. Th-stopping is possible among speakers of lower-class backgrounds. In addition, traces of a pitch accent as in Swedish and Norwegian can persist in some areas of heavy Norwegian or Swedish settlement, and among people who grew up in those areas (some of whom are not of Scandinavian descent). Also, sometimes the comparative form of adjectives are used in place of the root form of the adjective (e.g., saying "the sky is bluer" when the person means "the sky is blue" is common in Minnesota).[citation needed]

The appearance of monophthongs in this region is sometimes explained because of the high degree of Scandinavian and German immigration to these northern states in the late 1800s. Linguist Erik R. Thomas argues that these monophthongs are the product of language contact and notes that other areas where they occur are places where speakers of other languages have had an influence such as the Pennsylvania "Dutch" region.[9] An alternative account posits that these monophthongal variants represent historical retentions, since diphthongization of the mid vowels seems to have been a relatively recent phenomenon in the history of the English language, appearing within the last few centuries, and did not affect all dialects in the U.K. The monophthongs heard in this region may stem from the influence of Scots-Irish or other British dialects that maintain such forms. The fact that the monophthongs also appear in Canadian English may lend support to this account since Scots-Irish speech is known as an important influence in Canada.

Ethnic makeup of the US in 2000; the western part of Michigan's Upper Peninsula is the only region in the U.S. where Finnish Americans (medium light green) form the plurality. Likewise, Norwegian Americans (very light green) uniquely form the plurality in parts of Minnesota, North Dakota, and northeastern-most Montana.

People living in the Upper Peninsula of Michigan (whose demonym, and sometimes sub-dialect, is known as "Yooper," deriving from the acronym "U.P." for "Upper Peninsula"), many northern areas of the Lower Peninsula of Michigan, and in Northeast Wisconsin are largely of Finnish, French Canadian, Cornish, Scandinavian, German, and/or Native American descent. The North Central dialect is so strongly influenced by these areas' languages and Canada that speakers from other areas may have difficulty understanding it. Almost half the Finnish immigrants to the U.S. settled in the Upper Peninsula, some joining Scandinavians who moved on to Minnesota. Another sub-dialect is spoken in Southcentral Alaska's Matanuska-Susitna Valley, because it was settled in the 1930s (during the Great Depression) by immigrants from the North Central dialect region.[5][10]

In this dialect, the prepositionwith is used without an object as an adverb in phrases like come with, as in Do you want to come with? for standard Do you want to come with me? or with us?. In standard English, other prepositions can be used as adverbs, like go down (down as adverb) for go down the stairs (down as preposition). With is not typically used in this way in standard English (particularly in British and Irish English because of being distinguished as the original form of the English language), and this feature likely came from languages spoken by some immigrants, such as Scandinavian (Danish, Swedish, Norwegian), German (includes Austrian), or Dutch (includes Flemish and Luxembourgish), all of which have this construction, like Swedish kom med.[11][12]

Also, sometimes the comparative form of adjectives are used in place of the root form of the adjective.[citation needed]